The study of the history of phylogeny and diversification of Rhododendron genus has made new progress in the plant of Kunming

The results show that the chloroplast genome can well solve the phylogenetic relationship
between subgenera and most species of Rhododendron genus.
Compared with the previous phylogeny inferred based on chloroplast genome and nuclear genome data, it was found that Rhododendron included 13 stable monophyletic branches.
The strong conflict between nuclear and plastid phylogeny suggests that deep branching may have occurred Reticular evolutionary events
such as hybridization/gene intellation.
Subgenus R.
subg.
leaf bract (R.
subg .
Therorhodion) in the Eocene (c.
56 Mya).
It first differentiates and passes through the Eocene and Oligocene (about 32 My a ) was a relatively short period (about 6 my) in the early Miocene (23.
8 ~ 17.
6 Mya a) rapidly diversified to form 10 clades of the core genus Rhododendron (12 clades in total
).
The diversity histories of the two subgenera (representing more than 90per cent of the species in the region) with the Hengduan Mountains and the Himalayan region as the centres of differentiation are different.

Rhododendron subgenus (R.
subg Rhododendron) originated in the early Miocene (20.
1 Mya), with a rate of diversification in the subsequent ().
About 16.
6 mya) increased significantly, after which (about 13.
7mya) it redifferentiated to adapt to high altitudes (Clade RH) and adapted to the lower altitude (Clade RL), which is the same as Hengduan Mountain - The continuous geological tectonic events in the middle Miocene (about 17 ~ 14 mya) in the Himalayas coincide
with uplift to close to the present altitude.
Continuous active orogeny, climate cooling, and intensified Asian summer monsoon have contributed to the formation of parallel radiation speciation
in these two branches.
Another subgenus, R.
subg.
(R.
subg.
) with the Hengduan Mountains and Himalayan regions as the center of differentiation Hymenanthes) originated late in the early Miocene (1 9.
5 mya), and its crown group was in the late Miocene (about 10 m ya) began to diverge, and the rate of diversification began more slowly, spreading to Hengduan Mountain in the morning Miocene (about 5 Mya).
- Rapid radiation differentiation occurs in the Himalayas, with a net diversification rate nearly 5 times higher than that of the subgenus Rhododendron species.

This is most likely due to its spread in the Hengduan Mountains and Himalayas, where global cooling and monsoon strengthening during the Pliocene may have directly affected the rate
of differentiation.
The subgenus Evergreen Rhododendron contains only species adapted to high altitudes, but most of them The clade has species adapted to both low and high altitudes; Compared with the Rhododendron subgenus, its altitude preference plasticity is stronger, indicating that the subgenus has strong ecological plasticity in the process of diversification
.
This study provides an important case study
for understanding the history of species diversity formation and adaptive evolution in the Hengduanshan-Himalayan region.